JPWO2020149320A1 - Manufacturing method of grain-oriented electrical steel sheet - Google Patents

Manufacturing method of grain-oriented electrical steel sheet Download PDF

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JPWO2020149320A1
JPWO2020149320A1 JP2020566440A JP2020566440A JPWO2020149320A1 JP WO2020149320 A1 JPWO2020149320 A1 JP WO2020149320A1 JP 2020566440 A JP2020566440 A JP 2020566440A JP 2020566440 A JP2020566440 A JP 2020566440A JP WO2020149320 A1 JPWO2020149320 A1 JP WO2020149320A1
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less
annealing
decarburization
hot
steel sheet
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JP7188459B2 (en
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義行 牛神
修一 中村
浩康 藤井
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Nippon Steel Corp
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Nippon Steel Corp
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Abstract

この方向性電磁鋼板の製造方法は、珪素鋼素材を製造する珪素鋼素材製造工程と、前記珪素鋼素材を熱間圧延して熱延板を得る熱間圧延工程と、前記熱延板に一回の冷間圧延もしくは中間焼鈍を挟む複数回の冷間圧延を施して最終板厚の鋼板を得る冷間圧延工程と、前記鋼板に、加熱帯と均熱帯を備える脱炭焼鈍炉を用いて脱炭焼鈍を施す脱炭焼鈍工程と、前記鋼板に、アルミナを主成分とする焼鈍分離剤を塗布し、仕上げ焼鈍を施す仕上げ焼鈍工程と、を含み、前記脱炭焼鈍工程では、前記珪素鋼素材のＣｒ含有量を質量％でＸとしたとき、前記加熱帯の雰囲気ガスの酸化度Ｐ１が下記の式１を満足し、かつ前記均熱帯の雰囲気ガスの酸化度Ｐ２が下記の式２を満足する。０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）０．０１≦Ｐ２≦０．１５ （式２）The method for manufacturing this directional electromagnetic steel plate includes a silicon steel material manufacturing process for manufacturing a silicon steel material, a hot rolling process for hot rolling the silicon steel material to obtain a hot rolled plate, and a hot rolled plate. A cold rolling process to obtain a steel plate with the final plate thickness by performing cold rolling several times or cold rolling with intermediate annealing sandwiched between them, and a decarburization blunting furnace equipped with a heating zone and soaking zone for the steel plate. The decarburization and anneal step includes a decarburization and anneal step of applying a decarburization separating agent containing alumina as a main component to the steel plate and a finish anneal by applying a finish anneal. When the Cr content of the material is X by mass%, the degree of oxidation P1 of the atmospheric gas in the heated zone satisfies the following formula 1, and the degree of oxidation P2 of the atmospheric gas in the uniform tropical zone is the following formula 2. I am satisfied. 0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1) 0.01 ≤ P2 ≤ 0.15 (Equation 2)

Description

本発明は、方向性電磁鋼板の製造方法に関する。
本願は、２０１９年０１月１６日に、日本に出願された特願２０１９−００５１２８号に基づき優先権を主張し、その内容をここに援用する。The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet.
The present application claims priority based on Japanese Patent Application No. 2019-005128 filed in Japan on January 16, 2019, the contents of which are incorporated herein by reference.

方向性電磁鋼板は、軟磁性材料であり、主に、変圧器の鉄心材料として用いられる。そのため、方向性電磁鋼板には、高磁化特性および低鉄損という磁気特性が要求される。磁化特性とは、鉄心を励磁したときに誘起される磁束密度である。磁束密度が高いほど、鉄心を小型化できるので、変圧器の装置構成の点で有利であり、かつ変圧器の製造コストの点でも有利である。 Electrical steel sheets are soft magnetic materials and are mainly used as iron core materials for transformers. Therefore, grain-oriented electrical steel sheets are required to have magnetic properties such as high magnetization characteristics and low iron loss. The magnetization characteristic is the magnetic flux density induced when the iron core is excited. The higher the magnetic flux density, the smaller the iron core can be, which is advantageous in terms of the device configuration of the transformer and also in terms of the manufacturing cost of the transformer.

磁化特性を高くするためには、鋼板面に平行に｛１１０｝面が揃い、かつ、圧延方向に〈１００〉軸が揃った結晶方位（ゴス方位）となるように集合組織を制御する必要がある。結晶方位をゴス方位に集積するために、ＡｌＮ、ＭｎＳ、および、ＭｎＳｅなどのインヒビターを鋼中に微細に析出させて、二次再結晶を制御することが、通常行われている。 In order to improve the magnetization characteristics, it is necessary to control the texture so that the {110} planes are aligned parallel to the steel plate plane and the crystal orientation (goth orientation) is aligned with the <100> axis in the rolling direction. be. In order to accumulate the crystal orientation in the Goth orientation, it is usual practice to finely precipitate inhibitors such as AlN, MnS, and MnSe in the steel to control secondary recrystallization.

また、磁気特性としては、磁束密度（８００Ａ／ｍの磁場を付与したときの磁束密度Ｂ８値で代表される）が高く、鉄損（磁束密度１．７テスラ（Ｔ）、周波数５０ヘルツ（Ｈｚ）のエネルギー損失Ｗ１７／５０（Ｗ／ｋｇ）で代表される）が低いことが要求される。As for the magnetic characteristics, the magnetic flux density (represented by the magnetic flux density B8 value when a magnetic field of 800 A / m is applied) is high, and the iron loss (magnetic flux density 1.7 tesla (T), frequency 50 hertz (Hz)). ) Is required to have a low energy loss (represented by W 17/50 (W / kg)).

鉄損とは、鉄心を交流磁場で励磁した場合に、熱エネルギーとして消費される電力損失である。省エネルギーの観点から、鉄損はできるだけ低いことが求められる。鉄損の高低には、磁化率、板厚、皮膜張力、不純物量、電気抵抗率、結晶粒径、磁区サイズなどが影響する。電磁鋼板に関し、様々な技術が開発されている現在においても、エネルギー効率を高めるため、鉄損を低減する研究開発が継続されている。 The iron loss is the power loss consumed as heat energy when the iron core is excited by an AC magnetic field. From the viewpoint of energy saving, iron loss is required to be as low as possible. Magnetic susceptibility, plate thickness, film tension, amount of impurities, electrical resistivity, crystal grain size, magnetic domain size, etc. affect the level of iron loss. Even now that various technologies for electrical steel sheets are being developed, research and development to reduce iron loss is being continued in order to improve energy efficiency.

電磁鋼板が積み鉄心として用いられる場合、仕上げ焼鈍後の鋼板にレーザービームを照射して局部的な微小歪を与えることにより磁区を細分化して鉄損を低減させる方法が、特許文献１（特公昭５８−２６４０５号公報）に開示されている。 When an electromagnetic steel sheet is used as a stacked iron core, a method of irradiating a steel sheet after finish annealing with a laser beam to give local minute strain to subdivide the magnetic domain and reduce iron loss is described in Patent Document 1 (Tokukosho). 58-26405 (Ab. 58-26405).

また、電磁鋼板が巻き鉄心として用いられる場合には、鉄心に加工した後、歪取り焼鈍（Ｓｔｒｅｓｓ Ｒｅｌｅａｓｅ Ａｎｎｅａｌｉｎｇ：応力除去焼鈍）を施しても磁区細分化効果が消失しない方法が、特許文献２（特開昭６２−８６１７５号公報）に開示されている。これらの技術的手段を用いて磁区を細分化することにより、鉄損は大きく低減される。 Further, when an electromagnetic steel sheet is used as a wound iron core, Patent Document 2 (Patent Document 2) provides a method in which the magnetic domain subdivision effect does not disappear even if strain relief annealing (stress relief annealing) is performed after processing the iron core. It is disclosed in Japanese Patent Application Laid-Open No. 62-86175). By subdividing the magnetic domain using these technical means, iron loss is greatly reduced.

しかしながら、本発明者らが、上記のような磁区細分化を行った場合の磁区の動きを観察したところ、動かない磁区も存在することが判明した。そこで本発明者らは、方向性電磁鋼板の鉄損値をさらに低減するためには、磁区を細分化すると同時に、鋼板表面のグラス皮膜によって生じる、磁区の動きを阻害するピン止め効果をなくすことが重要であるとの認識に至った。 However, when the present inventors observed the movement of the magnetic domain when the magnetic domain was subdivided as described above, it was found that some magnetic domains did not move. Therefore, in order to further reduce the iron loss value of the grain-oriented electrical steel sheet, the present inventors should subdivide the magnetic domain and at the same time eliminate the pinning effect that hinders the movement of the magnetic domain caused by the glass film on the surface of the steel sheet. Came to the recognition that is important.

上述のような磁区移動の容易化を図るためには、鋼板表面にグラス皮膜を形成させないことが有効である。その手段として、粗大な高純度アルミナを焼鈍分離剤として用いることにより鋼板表面にグラス皮膜を形成させない方法が、特許文献３（米国特許第３７８５８８２号明細書）に開示されている。しかしながら、この方法では表面直下の介在物をなくすことができず、鉄損の向上代は、Ｗ１５／６０で高々２％に過ぎない。In order to facilitate the movement of magnetic domains as described above, it is effective not to form a glass film on the surface of the steel sheet. As a means for this, Patent Document 3 (US Pat. No. 3,758,882) discloses a method of preventing a glass film from being formed on the surface of a steel sheet by using coarse high-purity alumina as an annealing separator. However, this method cannot eliminate inclusions directly under the surface, and the improvement margin of iron loss is only 2% at W 15/60.

この表面直下の介在物を制御し、かつ表面の鏡面化を達成する方法として、仕上げ焼鈍後に化学研磨或いは電解研磨を行う方法が、特許文献４（特開昭６４−８３６２０号公報）に開示されている。しかしながら、化学研磨・電解研磨等の方法は、実験室レベルの試料の材料を加工することは可能であるが、上記方法を工業的規模で行うためには、薬液の濃度、温度の管理や、公害対策設備等の設置の問題を解決しなければならない。さらに、生産性の観点から、上記方法を実用化することは大変困難である。 Patent Document 4 (Japanese Unexamined Patent Publication No. 64-83620) discloses a method of performing chemical polishing or electrolytic polishing after finish annealing as a method of controlling inclusions directly under the surface and achieving mirroring of the surface. ing. However, although it is possible to process the material of the sample at the laboratory level by the methods such as chemical polishing and electrolytic polishing, in order to carry out the above method on an industrial scale, it is necessary to control the concentration and temperature of the chemical solution. The problem of installing pollution control equipment, etc. must be solved. Further, from the viewpoint of productivity, it is very difficult to put the above method into practical use.

この問題点を解消する方法として、脱炭焼鈍を、Ｆｅ系酸化物（Ｆｅ２ＳｉＯ４，ＦｅＯ等）が形成されない酸化度の雰囲気ガス中で行い、板間の焼鈍分離剤としてアルミナを用いる方法が、特許文献５（特開平０７−１１８７５０号公報）に開示されている。しかしながら、本プロセスを工業的に実施しようとしても、安定的に脱炭を進行させつつ良好な磁気特性を得ることは困難であることが判明してきた。As a method for solving this problem, decarburization annealing is performed in an atmosphere gas having an oxidation degree at which Fe-based oxides (Fe 2 SiO 4 , FeO, etc.) are not formed, and alumina is used as an annealing separator between plates. Is disclosed in Patent Document 5 (Japanese Unexamined Patent Publication No. 07-118750). However, even if this process is to be carried out industrially, it has been found that it is difficult to obtain good magnetic properties while stably proceeding with decarburization.

日本国特公昭５８−０２６４０５号公報Japan Special Issue No. 58-026405 日本国特開昭６２−８６１７５号公報Japanese Patent Application Laid-Open No. 62-86175 米国特許第３７８５８８２号明細書U.S. Pat. No. 3,758,882 日本国特開昭６４−０８３６２０号公報Japanese Patent Application Laid-Open No. 64-083620 日本国特開平０７−１１８７５０号公報Japanese Patent Application Laid-Open No. 07-118750

本発明は上述のような問題に鑑みてなされたものであり、脱炭焼鈍における脱炭を良好に実施しつつ、かつ磁気特性が良好である方向性電磁鋼板を製造するための方法を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems, and provides a method for manufacturing a grain-oriented electrical steel sheet having good magnetic properties while satisfactorily performing decarburization in decarburization annealing. The purpose is.

（１）本発明の一態様に係る方向性電磁鋼板の製造方法は、珪素鋼素材を製造する珪素鋼素材製造工程と、珪素鋼素材を熱間圧延して熱延板を得る熱間圧延工程と、前記熱延板に一回の冷間圧延もしくは中間焼鈍を挟む複数回の冷間圧延を施して最終板厚の鋼板を得る冷間圧延工程と、前記鋼板に、加熱帯と均熱帯を備える脱炭焼鈍炉を用いて脱炭焼鈍を施す脱炭焼鈍工程と、前記鋼板に、アルミナを主成分とする焼鈍分離剤を塗布し、仕上げ焼鈍を施す仕上げ焼鈍工程と、を含み、前記珪素鋼素材が、質量％で、Ｓｉ：０．８〜７．０％、Ｃ：０．０８５％以下、酸可溶性Ａｌ：０．０１０〜０．０６５％、Ｎ：０．００４〜０．０１２％、Ｍｎ：１．００％以下、Ｓ：０．０５０％以下、およびＣｒ：０．０２〜０．５０％を含有し、残部がＦｅ及び不純物からなり、前記脱炭焼鈍工程では、前記珪素鋼素材のＣｒ含有量を質量％でＸとしたとき、前記加熱帯の雰囲気ガスの酸化度Ｐ１が下記の式１を満足し、かつ前記均熱帯の雰囲気ガスの酸化度Ｐ２が下記の式２を満足する。
０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）
０．０１≦Ｐ２≦０．１５ （式２）(1) The method for manufacturing a directional electromagnetic steel sheet according to one aspect of the present invention is a silicon steel material manufacturing process for manufacturing a silicon steel material and a hot rolling step for hot rolling the silicon steel material to obtain a hot rolled plate. A cold rolling process in which the hot-rolled sheet is cold-rolled once or cold-rolled a plurality of times with intermediate annealing sandwiched between them to obtain a steel sheet with the final plate thickness, and a heating zone and soaking tropics are applied to the steel sheet. The silicon includes a decarburization and annealing step of decarburizing and annealing using a decarburized and annealed furnace provided, and a finish annealing step of applying a annealing separator containing alumina as a main component to the steel plate and performing a finish anneading. The weight of the steel material is Si: 0.8 to 7.0%, C: 0.085% or less, acid-soluble Al: 0.010 to 0.065%, N: 0.004 to 0.012%. , Mn: 1.00% or less, S: 0.050% or less, and Cr: 0.02 to 0.50%, the balance consists of Fe and impurities, and in the decarburization and rolling step, the silicon steel When the Cr content of the material is X by mass%, the degree of oxidation P1 of the atmospheric gas in the heated zone satisfies the following formula 1, and the degree of oxidation P2 of the atmospheric gas in the uniform tropical zone is the following formula 2. I am satisfied.
0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1)
0.01 ≤ P2 ≤ 0.15 (Equation 2)

（２）上記（１）に記載の方向性電磁鋼板の製造方法では、前記Ｐ１が下記の式３を満足してもよい。
０．３Ｘ＋０．０２５≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式３）(2) In the method for manufacturing grain-oriented electrical steel sheets according to (1) above, P1 may satisfy the following formula 3.
0.3X + 0.025 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 3)

（３）上記（１）又は（２）に記載の方向性電磁鋼板の製造方法では、前記Ｐ１、および前記Ｐ２が下記の式４を満足してもよい。
Ｐ１＞Ｐ２ （式４）(3) In the method for manufacturing grain-oriented electrical steel sheets according to (1) or (2) above, P1 and P2 may satisfy the following formula 4.
P1> P2 (Equation 4)

（４）上記（１）から（３）のいずれか１項に記載の方向性電磁鋼板の製造方法では、前記珪素鋼素材が、さらに、質量％で、Ｃｕ：０％以上０．４％以下、Ｐ：０％以上０．５％以下、Ｎｉ：０％以上１．０％以下、Ｂ：０％以上０．００８％以下、Ｖ：０％以上０．１５％以下、Ｎｂ：０％以上０．２０％以下、Ｍｏ：０％以上０．１０％以下、Ｔｉ：０％以上０．０１５％以下、及びＢｉ：０％以上０．０１０％以下を含有してもよい。 (4) In the method for producing a directional electromagnetic steel sheet according to any one of (1) to (3) above, the silicon steel material is further, in terms of mass%, Cu: 0% or more and 0.4% or less. , P: 0% or more and 0.5% or less, Ni: 0% or more and 1.0% or less, B: 0% or more and 0.008% or less, V: 0% or more and 0.15% or less, Nb: 0% or more It may contain 0.20% or less, Mo: 0% or more and 0.10% or less, Ti: 0% or more and 0.015% or less, and Bi: 0% or more and 0.010% or less.

（５）上記（１）から（４）のいずれか１項に記載の方向性電磁鋼板の製造方法では、脱炭焼鈍工程の前から前記仕上げ焼鈍工程での二次再結晶発現前までに、窒化処理工程をさらに含んでもよい。 (5) In the method for manufacturing grain-oriented electrical steel sheets according to any one of (1) to (4) above, from before the decarburization annealing step to before the development of secondary recrystallization in the finish annealing step. A nitriding process may be further included.

（６）上記（１）から（５）のいずれか１項に記載の方向性電磁鋼板の製造方法では、前記熱間圧延工程の後、かつ前記冷間圧延工程の前に、前記熱間圧延工程で得られた前記熱延板を焼鈍する熱延板焼鈍工程をさらに含んでもよい。 (6) In the method for manufacturing a directional electromagnetic steel sheet according to any one of (1) to (5) above, the hot rolling is performed after the hot rolling step and before the cold rolling step. A hot-rolled plate annealing step of annealing the hot-rolled plate obtained in the step may be further included.

本発明の上記態様によれば、脱炭焼鈍における脱炭を良好に実施しつつ、かつ磁気特性が良好である方向性電磁鋼板が得られる、方向性電磁鋼板の製造方法を提供できる。 According to the above aspect of the present invention, it is possible to provide a method for manufacturing a grain-oriented electrical steel sheet, which can obtain a grain-oriented electrical steel sheet having good magnetic characteristics while satisfactorily performing decarburization in decarburization annealing.

本発明の一実施形態に係る方向性電磁鋼板の製造方法を説明するためのフローチャートである。It is a flowchart for demonstrating the manufacturing method of the grain-oriented electrical steel sheet which concerns on one Embodiment of this invention. 実施例３の、Ｃｒ含有量Ｘ（質量％）と脱炭焼鈍の加熱帯の雰囲気ガス酸化度Ｐ１との関係性を示すグラフである。It is a graph which shows the relationship between the Cr content X (mass%) of Example 3 and the atmospheric gas oxidation degree P1 of the heating zone of decarburization annealing.

従来、方向性電磁鋼板の磁気特性を改善させるべく、上述のような検討がなされてきたが、依然として解決すべき上記のような課題がある。本発明者らは、このような課題を解決するために種々の実験を行った。その結果、鋼成分としてＣｒを適量含有させると共に、脱炭焼鈍工程の均熱帯と加熱帯の雰囲気ガスの酸化度（ＰＨ２Ｏ／ＰＨ２）とを制御することによって、脱炭を良好に実施しつつ磁気特性の良好な方向性電磁鋼板を製造することができることを見出した。Conventionally, the above-mentioned studies have been made in order to improve the magnetic properties of grain-oriented electrical steel sheets, but there are still the above-mentioned problems to be solved. The present inventors have conducted various experiments in order to solve such a problem. As a result, decarburization was satisfactorily carried out by containing an appropriate amount of Cr as a steel component and controlling the soaking tropics in the decarburization annealing step and the degree of oxidation of the atmospheric gas in the heating zone ( PH2O / PH2). At the same time, it has been found that a grain-oriented electrical steel sheet having good magnetic characteristics can be manufactured.

以下に、本発明の好適な実施形態について説明する。ただし、本発明はこれらの実施形態に開示された構成のみに制限されることなく、本発明の趣旨を逸脱しない範囲で種々の変更が可能であることは自明である。
また、以下の実施形態の独立した各要素は、本発明の範囲において、互いに組み合わせ可能であることも自明である。Hereinafter, preferred embodiments of the present invention will be described. However, it is obvious that the present invention is not limited to the configurations disclosed in these embodiments, and various modifications can be made without departing from the spirit of the present invention.
It is also self-evident that the independent elements of the following embodiments can be combined with each other within the scope of the present invention.

また、以下の実施形態において、数値限定範囲には、下限値および上限値がその範囲に含まれる。ただし、「超」または「未満」と示す数値は、その値が数値範囲に含まれない。
また、特に断りのない限り、以下の実施形態における化学成分の「％」は「質量％」を意味する。Further, in the following embodiments, the numerical limit range includes the lower limit value and the upper limit value. However, the numerical value indicated as "greater than" or "less than" is not included in the numerical range.
Further, unless otherwise specified, "%" of the chemical composition in the following embodiments means "mass%".

以下に、本発明の一実施形態に係る方向性電磁鋼板の製造方法について説明する。 Hereinafter, a method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention will be described.

以下の実施形態に係る方向性電磁鋼板の製造方法は、珪素鋼素材を製造する珪素鋼素材製造工程と、珪素鋼素材を熱間圧延して熱延板を得る熱間圧延工程と、熱延板に一回の冷間圧延もしくは中間焼鈍を挟む複数回の冷間圧延を施して最終板厚の鋼板を得る冷間圧延工程と、鋼板に、加熱帯と均熱帯とを備える脱炭焼鈍炉を用いて脱炭焼鈍を施す脱炭焼鈍工程と、鋼板にアルミナを主成分とする焼鈍分離剤を塗布し、仕上げ焼鈍を施す仕上げ焼鈍工程と、を含み、珪素鋼素材が、質量％で、Ｓｉ：０．８〜７．０％、Ｃ：０．０８５％以下、酸可溶性Ａｌ：０．０１０〜０．０６５％、Ｎ：０．００４〜０．０１２％、Ｍｎ：１．００％以下、Ｓ：０．０５０％以下、およびＣｒ：０．０２〜０．５０％を含有し、残部がＦｅ及び不純物からなり、脱炭焼鈍工程では、珪素鋼素材のＣｒ含有量を質量％でＸとしたとき、加熱帯の雰囲気ガスの酸化度Ｐ１が下記の式１を満足し、かつ均熱帯の雰囲気ガスの酸化度Ｐ２が下記の式２を満足することを特徴とする。また、上述の実施形態に係る方向性電磁鋼板の製造方法では、熱間圧延工程の後、かつ冷間圧延工程の前に、熱間圧延工程で得られた熱延板を焼鈍する熱延板焼鈍工程をさらに含んでもよい。
０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）
０．０１≦Ｐ２≦０．１５ （式２）The method for manufacturing the directional electromagnetic steel sheet according to the following embodiments is a silicon steel material manufacturing process for manufacturing a silicon steel material, a hot rolling step for hot rolling the silicon steel material to obtain a hot rolled plate, and hot rolling. A cold rolling process in which a plate is cold-rolled once or cold-rolled multiple times with intermediate annealing sandwiched to obtain a steel plate with the final plate thickness, and a decarburized tanning furnace equipped with a heating zone and a soothing tropics on the steel plate. The silicon steel material is made up of% by mass, including a decarburization and annealing step of decarburizing and annealing using a steel sheet and a finish annealing step of applying a annealing separator containing alumina as a main component to a steel plate and performing a finish anneading. Si: 0.8 to 7.0%, C: 0.085% or less, acid-soluble Al: 0.010 to 0.065%, N: 0.004 to 0.012%, Mn: 1.00% or less , S: 0.050% or less, and Cr: 0.02 to 0.50%, the balance consists of Fe and impurities, and in the decarburization and rolling step, the Cr content of the silicon steel material is X by mass%. Then, the degree of oxidation P1 of the atmosphere gas in the heated zone satisfies the following formula 1, and the degree of oxidation P2 of the atmosphere gas in the average tropical zone satisfies the following formula 2. Further, in the method for manufacturing a directional electromagnetic steel plate according to the above-described embodiment, the hot-rolled plate obtained by the hot-rolling step is annealed after the hot-rolling step and before the cold-rolling step. An annealing step may be further included.
0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1)
0.01 ≤ P2 ≤ 0.15 (Equation 2)

［珪素鋼素材の化学成分］
Ｓｉは、含有量を多くすると電気抵抗が高くなり、鉄損特性が改善される。しかし、Ｓｉ含有量が７．０％を超えると冷延が極めて困難となり、圧延時に鋼素材割れてしまう。そのため、Ｓｉ含有量の上限を７．０％とする。Ｓｉ含有量の上限は好ましくは４．５％、さらに好ましくは４．０％である。
また、Ｓｉ含有量が０．８％より少ないと、仕上げ焼鈍時にγ変態が生じ、鋼板の結晶方位が損なわれてしまう。そのため、Ｓｉ含有量の下限を０．８％とする。Ｓｉ含有量の下限は、好ましくは２．０％、さらに好ましくは２．５％である。[Chemical composition of silicon steel material]
When the content of Si is increased, the electric resistance becomes high and the iron loss characteristic is improved. However, if the Si content exceeds 7.0%, cold rolling becomes extremely difficult and the steel material cracks during rolling. Therefore, the upper limit of the Si content is set to 7.0%. The upper limit of the Si content is preferably 4.5%, more preferably 4.0%.
Further, if the Si content is less than 0.8%, γ transformation occurs at the time of finish annealing, and the crystal orientation of the steel sheet is impaired. Therefore, the lower limit of the Si content is set to 0.8%. The lower limit of the Si content is preferably 2.0%, more preferably 2.5%.

Ｃは、一次再結晶組織を制御するうえで有効な元素であるが、磁気特性に悪影響を及ぼすので、仕上げ焼鈍前に脱炭処理を施して除去する必要がある。
珪素鋼素材のＣ含有量が０．０８５％より多いと、脱炭焼鈍時間が長くなり、工業生産における生産性が損なわれてしまう。そのため、Ｃ含有量の上限を０．０８５％とする。Ｃ含有量の上限は、好ましくは０．０７０％である。C is an element effective in controlling the primary recrystallization structure, but since it adversely affects the magnetic properties, it needs to be removed by decarburization before finish annealing.
If the C content of the silicon steel material is more than 0.085%, the decarburization annealing time becomes long and the productivity in industrial production is impaired. Therefore, the upper limit of the C content is set to 0.085%. The upper limit of the C content is preferably 0.070%.

酸可溶性Ａｌは、本実施形態に係る方向性電磁鋼板の製造方法において、Ｎと結合して、（Ａｌ，Ｓｉ）Ｎとしてインヒビターとしての機能を果たすために必須の元素である。酸可溶性Ａｌ含有量は、二次再結晶が安定する０．０１０〜０．０６５％とする。
酸可溶性Ａｌ含有量の下限は、好ましくは０．０２０％、さらに好ましくは０．０２５％である。酸可溶性Ａｌ含有量の上限は、好ましくは０．０４０％、さらに好ましくは０．０３０％である。Acid-soluble Al is an essential element for binding to N and functioning as an inhibitor as (Al, Si) N in the method for producing grain-oriented electrical steel sheets according to the present embodiment. The acid-soluble Al content is 0.010 to 0.065%, which stabilizes secondary recrystallization.
The lower limit of the acid-soluble Al content is preferably 0.020%, more preferably 0.025%. The upper limit of the acid-soluble Al content is preferably 0.040%, more preferably 0.030%.

Ｎ含有量が０．０１２％を超えると、冷延時、鋼板中にブリスターとよばれる空孔が生じるので、Ｎ含有量は０．０１２％を超えないようにすることが好ましい。また、Ａｌと結合してインヒビターとしての機能を果たすためには、Ｎ含有量を０．００４％以上とする必要がある。Ｎ含有量の下限は、好ましくは０．００６％、さらに好ましくは０．００７％である。Ｎ含有量の上限は、好ましくは０．０１０％、さらに好ましくは０．００９％である。 If the N content exceeds 0.012%, pores called blisters are formed in the steel sheet during cold spreading, so it is preferable that the N content does not exceed 0.012%. Further, in order to bind to Al and fulfill the function as an inhibitor, the N content needs to be 0.004% or more. The lower limit of the N content is preferably 0.006%, more preferably 0.007%. The upper limit of the N content is preferably 0.010%, more preferably 0.009%.

Ｍｎ、Ｓは、熱間圧延における割れの発生を防止する観点からＭｎ／Ｓ≧４となるような範囲で含有させることが望ましい。一方、Ｍｎ含有量を多くすると飽和磁束が低下してしまうので、Ｍｎ含有量は１．００％以下とすることが好ましい。Ｓ含有量は好ましくは０．０５０％以下であり、より好ましくは０．０１５％以下、さらに好ましくは０．０１０％以下、一層好ましくは０．００７％以下の範囲である。
また、Ｓはその一部をＳｅで置き換えることができる。そのため、Ｓｅを含む場合、Ｓ＋Ｓｅ：０．０５０％以下であることが好ましく、Ｍｎ／（Ｓ＋Ｓｅ）≧４となる範囲であることが好ましい。It is desirable that Mn and S are contained in a range such that Mn / S ≧ 4 from the viewpoint of preventing the occurrence of cracks in hot rolling. On the other hand, if the Mn content is increased, the saturation magnetic flux decreases, so the Mn content is preferably 1.00% or less. The S content is preferably 0.050% or less, more preferably 0.015% or less, still more preferably 0.010% or less, still more preferably 0.007% or less.
Further, S can partially replace a part thereof with Se. Therefore, when Se is included, S + Se: 0.050% or less is preferable, and Mn / (S + Se) ≧ 4 is preferable.

ＭｎとＳは、二次再結晶のインヒビターとして活用される場合がある。この場合、二次再結晶が安定するＭｎ含有量は、０．０２〜０．３０％の範囲である。Ｍｎ含有量の下限は、好ましくは０．０５％であり、さらに好ましくは０．０７％である。Ｍｎ含有量の上限は、好ましくは０．１５％、さらに好ましくは０．１０％である。また、この場合、好ましいＳ含有量は、０．０１０〜０．０５０％の範囲である。Ｓの含有量は、好ましくは０．０１５％以上、さらに好ましくは０．０２０％以上である。Ｓの含有量は、より好ましくは０．０４０％以下である。また、ＳをＳｅで置き換えることもできる。 Mn and S may be utilized as inhibitors of secondary recrystallization. In this case, the Mn content at which the secondary recrystallization is stable is in the range of 0.02 to 0.30%. The lower limit of the Mn content is preferably 0.05%, more preferably 0.07%. The upper limit of the Mn content is preferably 0.15%, more preferably 0.10%. Further, in this case, the preferable S content is in the range of 0.010 to 0.050%. The content of S is preferably 0.015% or more, more preferably 0.020% or more. The content of S is more preferably 0.040% or less. Further, S can be replaced with Se.

田口・坂倉等による製造法（たとえば特公昭４０−１５６４４号公報）においては、ＭｎとＳとは、二次再結晶のインヒビターとして活用する。
一方、小松等による製造法（たとえば特公昭６２−４５２８５号公報）においては、ＭｎとＳとは、二次再結晶のインヒビターとして用いない。In the production method by Taguchi, Sakakura, etc. (for example, Japanese Patent Publication No. 40-15644), Mn and S are utilized as inhibitors of secondary recrystallization.
On the other hand, in the production method by Komatsu et al. (For example, Japanese Patent Publication No. 62-45285), Mn and S are not used as inhibitors for secondary recrystallization.

Ｃｒは、脱炭焼鈍における酸化層形成挙動に影響を及ぼし、脱炭性を改善するとともにその後の表面平滑化を促進する元素である。
Ｃｒ含有量は、脱炭性の改善効果が得られる０．０２〜０．５０％とする。好ましくは、Ｃｒ含有量の下限は、０．０５％であり、好ましくは、Ｃｒ含有量の上限は、０．３９％である。Cr is an element that affects the oxide layer formation behavior in decarburization annealing, improves decarburization property, and promotes subsequent surface smoothing.
The Cr content is 0.02 to 0.50%, which is effective in improving decarburization. Preferably, the lower limit of the Cr content is 0.05%, and preferably the upper limit of the Cr content is 0.39%.

本実施形態では、珪素鋼素材の成分として、上記成分に加えて、必要に応じて、さらに、Ｃｕ、Ｎｉ、Ｐ、Ｍｏ、Ｂｉ、Ｂ、Ｖ、ＮｂおよびＴｉからなる群から選択される１種または２種以上を、質量％で、Ｃｕ：０〜０．４％、Ｎｉ：０〜１．０％、Ｐ：０〜０．５％、Ｍｏ：０〜０．１０％、Ｂｉ：０〜０．０１０％、Ｂ：０〜０．００８％、Ｖ：０〜０．１５％、Ｎｂ：０〜０．２０％、Ｔｉ：０〜０．０１５％の範囲で含有してもよい。 In the present embodiment, the component of the silicon steel material is selected from the group consisting of Cu, Ni, P, Mo, Bi, B, V, Nb and Ti, if necessary, in addition to the above components1. Seeds or two or more species in% by mass, Cu: 0-0.4%, Ni: 0-1.0%, P: 0-0.5%, Mo: 0-0.10%, Bi: 0 It may be contained in the range of ~ 0.010%, B: 0 to 0.008%, V: 0 to 0.15%, Nb: 0 to 0.20%, Ti: 0 to 0.015%.

Ｃｕ：０％以上０．４％以下
Ｃｕ（銅）は、電気抵抗を高めて鉄損を低減するのに有効な元素である。従って、Ｃｕを０．４％以下の含有量の範囲で含有させてもよい。Ｃｕ含有量が０．４％を超えると、鉄損低減効果が飽和してしまうとともに、熱間圧延時に“カッパーヘゲ”という表面疵の原因になることがある。Ｃｕ含有量の下限は、０．０５％であることが好ましく、０．１％であることがより好ましい。Ｃｕ含有量の上限は、０．３％であることが好ましく、０．２％であることがより好ましい。Cu: 0% or more and 0.4% or less Cu (copper) is an element effective for increasing electric resistance and reducing iron loss. Therefore, Cu may be contained in the range of 0.4% or less. If the Cu content exceeds 0.4%, the iron loss reducing effect is saturated, and it may cause a surface defect called "copper hegging" during hot rolling. The lower limit of the Cu content is preferably 0.05%, more preferably 0.1%. The upper limit of the Cu content is preferably 0.3%, more preferably 0.2%.

Ｎｉ：０％以上１．０％以下
Ｎｉ（ニッケル）は、電気抵抗を高めて鉄損を低減するのに有効な元素である。また、Ｎｉは、熱延板の金属組織を制御して、磁気特性を高めるうえで有効な元素である。従って、Ｎｉを１．０％以下の含有量の範囲で含有させてもよい。Ｎｉ含有量が１．０％を超えると、二次再結晶が不安定になることがある。Ｎｉ含有量の下限は、０．０１％であることが好ましく、０．０２％であることがより好ましい。Ｎｉ含有量の上限は、０．２％であることが好ましく、０．１％であることがより好ましい。Ni: 0% or more and 1.0% or less Ni (nickel) is an element effective for increasing electric resistance and reducing iron loss. Further, Ni is an effective element for controlling the metal structure of the hot-rolled plate and enhancing the magnetic properties. Therefore, Ni may be contained in the range of the content of 1.0% or less. If the Ni content exceeds 1.0%, secondary recrystallization may become unstable. The lower limit of the Ni content is preferably 0.01%, more preferably 0.02%. The upper limit of the Ni content is preferably 0.2%, more preferably 0.1%.

Ｐ：０％以上０．５％以下
Ｐ（燐）は、電気抵抗を高めて鉄損を低減するのに有効な元素である。従って、Ｐを０．５％以下の含有量の範囲で含有させてもよい。Ｐ含有量が０．５％を超えると、珪素鋼板の圧延性に問題が生じることがある。Ｐ含有量の下限は、０．００５％であることが好ましく、０．０１％であることがより好ましい。Ｐ含有量の上限は、０．２％であることが好ましく、０．１５％であることがより好ましい。P: 0% or more and 0.5% or less P (phosphorus) is an element effective for increasing electric resistance and reducing iron loss. Therefore, P may be contained in the range of 0.5% or less. If the P content exceeds 0.5%, there may be a problem in the rollability of the silicon steel sheet. The lower limit of the P content is preferably 0.005%, more preferably 0.01%. The upper limit of the P content is preferably 0.2%, more preferably 0.15%.

Ｍｏ：０％以上０．１０％以下
Ｍｏ（モリブデン）も、電気抵抗を高めて鉄損を低減するのに有効な元素である。従って、Ｍｏを０．１０％以下の含有量の範囲で含有させてもよい。Ｍｏ含有量が０．１０％を超えると、鋼板の圧延性に問題が生じることがある。Ｍｏ含有量の下限は、０．００５％であることが好ましく、０．０１％であることがより好ましい。Ｍｏ含有量の上限は、０．０８％であることが好ましく、０．０５％であることがより好ましい。Mo: 0% or more and 0.10% or less Mo (molybdenum) is also an effective element for increasing electrical resistance and reducing iron loss. Therefore, Mo may be contained in the range of 0.10% or less. If the Mo content exceeds 0.10%, a problem may occur in the rollability of the steel sheet. The lower limit of the Mo content is preferably 0.005%, more preferably 0.01%. The upper limit of the Mo content is preferably 0.08%, more preferably 0.05%.

Ｂｉ：０％以上０．０１０％以下
Ｂｉ（ビスマス）は、硫化物等の析出物を安定化してインヒビターとしての機能を強化するのに有効な元素である。従って、Ｂｉを０．０１０％以下の含有量の範囲で含有させてもよい。Ｂｉ含有量が０．０１０％を超えると、磁気特性が劣化することがある。Ｂｉ含有量の下限は、０．００１％であることが好ましく、０．００２％であることがより好ましい。Ｂｉ含有量の上限は、０．００８％であることが好ましく、０．００６％であることがより好ましい。Bi: 0% or more and 0.010% or less Bi (bismuth) is an element effective for stabilizing precipitates such as sulfides and enhancing the function as an inhibitor. Therefore, Bi may be contained in the range of 0.010% or less. If the Bi content exceeds 0.010%, the magnetic properties may deteriorate. The lower limit of the Bi content is preferably 0.001%, more preferably 0.002%. The upper limit of the Bi content is preferably 0.008%, more preferably 0.006%.

Ｂ：０％以上０．００８％以下
Ｂ（ホウ素）は、ＢＮとしてインヒビター効果を発揮する有効な元素である。従って、Ｂを０．００８％以下の含有量の範囲で含有させてもよい。Ｂ含有量が０．００８％を超えると、磁気特性が劣化するおそれがある。Ｂ含有量の下限は、０．０００５％であることが好ましく、０．００１％であることがより好ましい。Ｂ含有量の上限は、０．００５％であることが好ましく、０．００３％であることがより好ましい。B: 0% or more and 0.008% or less B (boron) is an effective element that exerts an inhibitory effect as BN. Therefore, B may be contained in the range of the content of 0.008% or less. If the B content exceeds 0.008%, the magnetic properties may deteriorate. The lower limit of the B content is preferably 0.0005%, more preferably 0.001%. The upper limit of the B content is preferably 0.005%, more preferably 0.003%.

Ｖ：０％以上０．１５％以下
Ｎｂ：０％以上０．２０％以下
Ｔｉ：０％以上０．０１５％以下
Ｖ（バナジウム）、Ｎｂ（ニオブ）、及びＴｉ（チタン）は、ＮやＣと結合してインヒビターとして機能する、有効な元素である。従って、Ｖを０．１５％以下、Ｎｂを０．２％以下、および／またはＴｉを０．０１５％以下の含有量の範囲で含有させてもよい。これらの元素が最終製品に残留して、Ｖ含有量が０．１５％を超え、Ｎｂ含有量が０．２０％を超え、またはＴｉ含有量が０．０１５％を超えると、磁気特性が劣化するおそれがある。
Ｖ含有量の下限は、０．００２％であることが好ましく、０．０１％であることがより好ましい。Ｖ含有量の上限は、０．１０％であることが好ましく、０．０５％であることがより好ましい。
Ｎｂ含有量の下限は、０．００５％であることが好ましく、０．０２％であることがより好ましい。Ｎｂ含有量の上限は、０．１０％であることが好ましく、０．０８％であることがより好ましい。
Ｔｉ含有量の下限は、０．００２％であることが好ましく、０．００４％であることがより好ましい。Ｔｉ含有量の上限は、０．０１０％であることが好ましく、０．００８％であることがより好ましい。V: 0% or more and 0.15% or less Nb: 0% or more and 0.20% or less Ti: 0% or more and 0.015% or less V (vanadium), Nb (niobium), and Ti (titanium) are N and C. It is an effective element that binds to and functions as an inhibitor. Therefore, V may be contained in the range of 0.15% or less, Nb in 0.2% or less, and / or Ti in the content of 0.015% or less. If these elements remain in the final product and the V content exceeds 0.15%, the Nb content exceeds 0.20%, or the Ti content exceeds 0.015%, the magnetic properties deteriorate. There is a risk of
The lower limit of the V content is preferably 0.002%, more preferably 0.01%. The upper limit of the V content is preferably 0.10%, more preferably 0.05%.
The lower limit of the Nb content is preferably 0.005%, more preferably 0.02%. The upper limit of the Nb content is preferably 0.10%, more preferably 0.08%.
The lower limit of the Ti content is preferably 0.002%, more preferably 0.004%. The upper limit of the Ti content is preferably 0.010%, more preferably 0.008%.

［方向性電磁鋼板の製造方法］
上述した化学組成の珪素鋼素材から｛１１０｝＜００１＞方位に発達した集合組織を有する方向性電磁鋼板を製造するためには、次のような工程を経る。[Manufacturing method of grain-oriented electrical steel sheet]
In order to produce a grain-oriented electrical steel sheet having an texture developed in the {110} <001> orientation from the silicon steel material having the above-mentioned chemical composition, the following steps are performed.

まず、上述の化学成分を有する溶鋼を鋳造して（Ｓ１００）珪素鋼素材を得て、この珪素鋼素材を通常の熱間圧延工程（Ｓ１０２）により熱延板とする。あるいは、熱間圧延工程（Ｓ１０２）に替えて、溶鋼を連続鋳造して薄帯としてもよい。 First, a molten steel having the above-mentioned chemical composition is cast (S100) to obtain a silicon steel material, and this silicon steel material is made into a hot-rolled plate by a normal hot rolling step (S102). Alternatively, instead of the hot rolling step (S102), molten steel may be continuously cast to form a thin band.

上記熱延板または連続鋳造薄帯は直ちに、もしくは熱延板焼鈍工程（Ｓ１０４）を経て、冷間圧延工程（Ｓ１０６）に供される。
熱延板焼鈍工程（Ｓ１０４）における焼鈍は、７５０〜１２００℃の温度域で３０秒〜３０分間行われてもよい。The hot-rolled plate or continuously cast strip is subjected to a cold rolling step (S106) immediately or through a hot-rolled plate annealing step (S104).
The annealing in the hot-rolled plate annealing step (S104) may be performed in a temperature range of 750 to 1200 ° C. for 30 seconds to 30 minutes.

熱延板焼鈍工程は製品の磁気特性を高めるために有効である。熱延板焼鈍工程の有無は、最終的に製造される方向性電磁鋼板に要求される特性及び製造コストに応じて決定すればよく、熱延板焼鈍工程は省略してもよい。 The hot-rolled sheet annealing process is effective for enhancing the magnetic properties of the product. The presence or absence of the hot-rolled sheet annealing step may be determined according to the characteristics and manufacturing cost required for the grain-oriented electrical steel sheet to be finally manufactured, and the hot-rolled sheet annealing step may be omitted.

冷間圧延工程（Ｓ１０６）における冷間圧延は、一回もしくは焼鈍を挟む複数の冷間圧延によって行う。一回の冷間圧延を行う場合には、圧下率を８０％以上とすることが好ましい。また、焼鈍を挟む複数の冷間圧延を行う場合、最終の焼鈍後の最終の冷間圧延の圧下率が８０％以上となることがより好ましい。この工程によって得られる冷延板は、最終板厚の鋼板である。 The cold rolling in the cold rolling step (S106) is performed once or by a plurality of cold rolling sandwiching annealing. When performing one cold rolling, the rolling reduction is preferably 80% or more. Further, when a plurality of cold rollings sandwiching annealing are performed, it is more preferable that the rolling reduction ratio of the final cold rolling after the final annealing is 80% or more. The cold-rolled plate obtained by this step is a steel plate having a final plate thickness.

冷間圧延後の材料は、鋼中に含まれる炭素を除去するために、脱炭焼鈍工程（Ｓ１０８）を経る。 The material after cold rolling undergoes a decarburization annealing step (S108) in order to remove carbon contained in the steel.

本実施形態に係る方向性電磁鋼板の製造方法では、脱炭焼鈍工程（Ｓ１０８）において、加熱帯と均熱帯とを備える脱炭焼鈍炉を用い、湿水素雰囲気中で脱炭焼鈍を行う。脱炭焼鈍工程（Ｓ１０８）の雰囲気ガスを鉄（Ｆｅ）系酸化物が形成されない酸化度に制御して焼鈍する。 In the method for producing a directional electromagnetic steel plate according to the present embodiment, in the decarburization annealing step (S108), decarburization annealing is performed in a moist hydrogen atmosphere using a decarburization annealing furnace provided with a heating zone and a soothing tropic. The atmospheric gas in the decarburization annealing step (S108) is annealed by controlling the degree of oxidation at which iron (Fe) -based oxides are not formed.

脱炭焼鈍工程（Ｓ１０８）における加熱帯の雰囲気ガスの酸化度Ｐ１は、下記の式１を満足するように制御する。
０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）The degree of oxidation P1 of the atmospheric gas in the heating zone in the decarburization annealing step (S108) is controlled so as to satisfy the following formula 1.
0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1)

式１中で、Ｘは珪素鋼素材のＣｒ含有量（質量％）を表し、Ｐ１は脱炭焼鈍工程（Ｓ１０８）における加熱帯の雰囲気ガスの酸化度を表す。酸化度Ｐ１は、水素、窒素、および水蒸気を含有する雰囲気ガスにおける水素分圧に対する水蒸気分圧の比「ＰＨ２Ｏ／ＰＨ２」で表される酸化度である。
脱炭焼鈍工程（Ｓ１０８）における加熱帯の雰囲気ガスの酸化度Ｐ１を上記の式１で規定することで、加熱帯において鋼板最表面にＣｒ酸化物を含有する形態の初期酸化膜が形成され、脱炭が好ましく進行すると考えられる。鉄系酸化膜は、たとえば後工程で塗布されるアルミナなどの焼鈍分離剤と反応して、表面平滑化を阻害すると考えられる。脱炭性は、加熱帯で最初に表面に形成される初期酸化膜に律速されるが、Ｃｒを含有させることで、Ｃｒ酸化物が初期酸化膜を変質させ、脱炭性が改善されると考えられる。In the formula 1, X represents the Cr content (mass%) of the silicon steel material, and P1 represents the degree of oxidation of the atmospheric gas in the heating zone in the decarburization annealing step (S108). The degree of oxidation P1 is the degree of oxidation expressed by the ratio of the partial pressure of water vapor to the partial pressure of hydrogen in an atmospheric gas containing hydrogen, nitrogen, and water vapor, " PH2O / PH2".
By defining the oxidation degree P1 of the atmospheric gas in the heating zone in the decarburization annealing step (S108) by the above formula 1, an initial oxide film containing Cr oxide is formed on the outermost surface of the steel sheet in the heating zone. Decarburization is considered to proceed favorably. It is considered that the iron-based oxide film reacts with an annealing separation agent such as alumina applied in a subsequent step to inhibit surface smoothing. The decarburization property is rate-determined by the initial oxide film first formed on the surface in the heating zone, but when Cr is contained, the Cr oxide changes the quality of the initial oxide film and the decarburization property is improved. Conceivable.

脱炭焼鈍工程（Ｓ１０８）における均熱帯の雰囲気ガスの酸化度Ｐ２は、下記の式２を満足するように制御する。
０．０１≦Ｐ２≦０．１５ （式２）The degree of oxidation P2 of the atmospheric gas in the tropical atmosphere in the decarburization annealing step (S108) is controlled so as to satisfy the following formula 2.
0.01 ≤ P2 ≤ 0.15 (Equation 2)

酸化度Ｐ２は、水素、窒素、および水蒸気を含有する雰囲気ガスにおける水素分圧に対する水蒸気分圧の比「ＰＨ２Ｏ／ＰＨ２」で表される酸化度である。The degree of oxidation P2 is the degree of oxidation expressed by the ratio of the partial pressure of water vapor to the partial pressure of hydrogen in an atmospheric gas containing hydrogen, nitrogen, and water vapor, " PH2O / PH2".

後の工程でアルミナを主成分とする焼鈍分離剤を塗布して鋼板を積層し、仕上げ焼鈍後の鋼板表面を平滑化させるためには、この脱炭焼鈍において、Ｆｅ系の酸化物（Ｆｅ２ＳｉＯ４，ＦｅＯ等）を形成させない酸化度で焼鈍を行うことが好ましい。たとえば、通常脱炭焼鈍が行われる８００〜８５０℃の温度域においては、均熱帯の雰囲気ガスの酸化度Ｐ２（ＰＨ２Ｏ／ＰＨ２）を０．１５以下に調整することにより、Ｆｅ系酸化物の生成を抑制することができる。In order to apply an annealing separator containing alumina as the main component in a later step to laminate steel plates and smooth the surface of the steel plates after finish annealing, Fe-based oxides (Fe 2) are used in this decarburization annealing. It is preferable to perform annealing at an oxidation degree that does not form SiO 4, FeO, etc.). For example, typically by in a temperature range of 800 to 850 ° C. for decarburization annealing is carried out, to adjust the oxidation degree of the atmospheric gas in the soaking zone P2 a (P H2O / P H2) to 0.15, Fe-based oxides Can be suppressed.

均熱帯の雰囲気ガスの酸化度Ｐ２が０．１５超の場合、製品の表面下に介在物が生成して、これが鉄損低下の障害となる。ただし、あまりに酸化度Ｐ２を下げると脱炭速度が遅くなってしまう。この両者を勘案すると、この温度域においては均熱帯の雰囲気ガスの酸化度Ｐ２（ＰＨ２Ｏ／ＰＨ２）は、０．０１〜０．１５の範囲であることが好ましい。When the oxidation degree P2 of the tropical atmosphere gas exceeds 0.15, inclusions are formed under the surface of the product, which hinders the reduction of iron loss. However, if the degree of oxidation P2 is lowered too much, the decarburization rate will be slowed down. Considering both of these, the degree of oxidation P2 ( PH2O / PH2 ) of the atmospheric gas in the tropical zone is preferably in the range of 0.01 to 0.15 in this temperature range.

脱炭焼鈍工程では、加熱帯の雰囲気ガスの酸化度Ｐ１は、下記の式３を満足することがより好ましい。
０．３Ｘ＋０．０２５≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式３）
式３中で、Ｘは珪素鋼素材のＣｒ含有量（質量％）を表す。In the decarburization annealing step, the oxidation degree P1 of the atmospheric gas in the heating zone more preferably satisfies the following formula 3.
0.3X + 0.025 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 3)
In Equation 3, X represents the Cr content (% by mass) of the silicon steel material.

また、脱炭焼鈍工程では、さらに良好な鉄損が得られるという観点からは、加熱帯の雰囲気ガスの酸化度Ｐ１と均熱帯の雰囲気ガスの酸化度Ｐ２とが下記の式４を満足することがより好ましい。
Ｐ１＞Ｐ２ （式４）Further, from the viewpoint that even better iron loss can be obtained in the decarburization annealing step, the oxidation degree P1 of the atmospheric gas in the heating zone and the oxidation degree P2 of the atmospheric gas in the tropical zone satisfy the following formula 4. Is more preferable.
P1> P2 (Equation 4)

脱炭工程において、室温から均熱帯の温度までの昇温速度（加熱帯の昇温速度）は、平均７℃／秒以上が好ましく、９℃／秒以上とすることがより好ましい。昇温速度が遅すぎると脱炭性が劣化する。また、上限について規定する必要はないが、速すぎると均熱温度を制御することが難しくなる。 In the decarburization step, the temperature rise rate from room temperature to the temperature of the tropics (heating rate of the heating zone) is preferably 7 ° C./sec or more on average, and more preferably 9 ° C./sec or more. If the heating rate is too slow, the decarburization property deteriorates. Further, it is not necessary to specify the upper limit, but if it is too fast, it becomes difficult to control the soaking temperature.

均熱帯の温度および均熱帯での保持時間は、７５０〜９００℃で、１０〜６００秒とすることが好ましい。均熱帯の温度（焼鈍温度）が７５０℃未満であると、脱炭速度が遅くなり生産性が低下する。一方、９００℃超であると一次再結晶粒径が所望のサイズを超えてしまうため、仕上げ焼鈍後の磁気特性が劣化する。また、保持時間が１０秒未満であると、脱炭を充分に行うことができない。一方、６００秒超であると生産性が低下する。 The temperature of the tropics and the retention time in the tropics are preferably 750 to 900 ° C., preferably 10 to 600 seconds. If the temperature of the tropics (annealing temperature) is less than 750 ° C., the decarburization rate becomes slow and the productivity decreases. On the other hand, if the temperature exceeds 900 ° C., the primary recrystallization grain size exceeds a desired size, so that the magnetic properties after finish annealing deteriorate. Further, if the holding time is less than 10 seconds, decarburization cannot be sufficiently performed. On the other hand, if it exceeds 600 seconds, the productivity decreases.

脱炭焼鈍工程（Ｓ１０８）の前から仕上げ焼鈍工程（Ｓ１１２）における二次再結晶が開始するまでの間に、窒化処理工程（Ｓ１１０）を含んでいてもよい。 The nitriding treatment step (S110) may be included from before the decarburization annealing step (S108) to the start of secondary recrystallization in the finish annealing step (S112).

この窒化処理の方法は特に限定するものではなく、アンモニア等の窒化能のある雰囲気ガス中で行う方法、窒化能のある窒化物を焼鈍分離剤に添加する方法等がある。
たとえば、窒化処理工程（Ｓ１１０）は、小松等による（Ａｌ，Ｓｉ）Ｎを主インヒビタ−として用いる製造法（特公昭６２−４５２８５号公報）等）の窒化処理が好ましく用いられる。The method of this nitriding treatment is not particularly limited, and there are a method of performing the nitriding treatment in an atmospheric gas having a nitriding ability such as ammonia, a method of adding a nitride having a nitriding ability to the annealing separator, and the like.
For example, in the nitriding treatment step (S110), the nitriding treatment of a production method (Japanese Patent Publication No. 62-45285) using (Al, Si) N as a main inhibitor by Komatsu et al. Is preferably used.

仕上げ焼鈍工程（Ｓ１１２）では、鋼板に、アルミナを主成分とする（アルミナを５０質量％以上含む）焼鈍分離剤を塗布する。焼鈍分離剤には、アルミナの他に、マグネシアを５〜５０質量％含有させることが好ましい。マグネシアを含有させると、鋼板表面のムライト（３Ａｌ２Ｏ３・２ＳｉＯ２）等の介在物形成が抑制され、鉄損が安定して向上する。
仕上げ焼鈍工程では、酸化層を有する鋼板の表面に、上記のアルミナを主成分とする焼鈍分離剤を塗布して乾燥させ、乾燥後、コイル状に巻き取って、仕上げ焼鈍（二次再結晶焼鈍）に供する。In the finish annealing step (S112), an annealing separator containing alumina as a main component (containing 50% by mass or more of alumina) is applied to the steel sheet. The annealing separator preferably contains 5 to 50% by mass of magnesia in addition to alumina. The inclusion of magnesia, is suppressed inclusions formed such mullite surface of the steel sheet (3Al 2 O 3 · 2SiO 2 ) is, iron loss is improved stably.
In the finish annealing step, the above-mentioned annealing separator containing alumina as a main component is applied to the surface of a steel sheet having an oxide layer, dried, dried, and then wound into a coil to perform finish annealing (secondary recrystallization annealing). ).

アルミナを主成分とする焼鈍分離剤を用いた場合、仕上げ焼鈍を行っても、鋼板表面にフォルステライトなどの無機鉱物質の皮膜が生成されることを抑制できる。 When an annealing separator containing alumina as a main component is used, it is possible to suppress the formation of a film of an inorganic mineral substance such as forsterite on the surface of the steel sheet even if finish annealing is performed.

焼鈍分離剤の塗布については、脱炭焼鈍板を積層（コイル）する際に、シリカと反応し難いアルミナを主成分とする焼鈍分離剤を水スラリーで、もしくは静電塗布法等により塗布することが好ましい。
この積層した脱炭焼鈍板を仕上げ焼鈍して、二次再結晶と窒化物や硫化物などの純化とを行う。二次再結晶を、一定の温度で保持する等の手段により所定の温度域で行うことは、磁束密度を上げるうえで有効である。
仕上げ焼鈍は例えば水素及び窒素を含有する雰囲気ガス中で、１１５０〜１２５０℃まで昇温し、１０〜３０時間焼鈍する条件で行えばよいが、窒化物や硫化物などの純化等を行う場合、二次再結晶完了後、１００％水素雰囲気中で１１００℃以上の温度で焼鈍することが好ましい。
上記のような仕上げ焼鈍後、表面が鏡面状となり、鉄損を大きく低下させることができる。Regarding the application of the annealing separator, when laminating (coiling) the decarburized annealing plate, the annealing separator containing alumina as the main component, which does not easily react with silica, should be applied with a water slurry or by an electrostatic coating method. Is preferable.
The laminated decarburized annealing plate is finished and annealed to perform secondary recrystallization and purification of nitrides and sulfides. Performing the secondary recrystallization in a predetermined temperature range by means such as holding the secondary recrystallization at a constant temperature is effective in increasing the magnetic flux density.
Finish annealing may be carried out under the condition of raising the temperature to 1150 to 1250 ° C. and annealing for 10 to 30 hours in an atmospheric gas containing hydrogen and nitrogen, but when purifying nitrides and sulfides, etc. After the completion of the secondary recrystallization, it is preferable to anneal at a temperature of 1100 ° C. or higher in a 100% hydrogen atmosphere.
After finish annealing as described above, the surface becomes mirror-like, and iron loss can be greatly reduced.

仕上げ焼鈍工程（Ｓ１１２）の後、絶縁皮膜形成工程（Ｓ１１４）において、鋼板の表面に、鋼板に張力を与える絶縁被膜を形成させる。 After the finish annealing step (S112), in the insulating film forming step (S114), an insulating film that gives tension to the steel sheet is formed on the surface of the steel sheet.

また、必要に応じて、上述した各工程の間で、歯形などによる機械的手法、エッチングなどによる化学的手法、レーザー照射や電子線の照射などによって磁区細分化処理を施してもよい。 Further, if necessary, magnetic domain subdivision processing may be performed between each of the above-mentioned steps by a mechanical method such as a tooth profile, a chemical method such as etching, laser irradiation, or electron beam irradiation.

以上のように、冷間圧延後の材料の鋼中に含まれる炭素を除去するために、湿水素雰囲気中で脱炭焼鈍を行う脱炭焼鈍工程において、雰囲気ガスを鉄系酸化物が形成されない酸化度に制御して焼鈍することが本発明の実施形態に係る方向性電磁鋼板の製造方法の主要な特徴である。 As described above, in the decarburization annealing step of performing decarburization annealing in a wet hydrogen atmosphere in order to remove carbon contained in the steel of the material after cold rolling, iron-based oxides are not formed in the atmosphere gas. Annealing by controlling the degree of oxidation is a major feature of the method for producing a directional electromagnetic steel sheet according to an embodiment of the present invention.

また、上述の実施形態に係る方向性電磁鋼板の製造方法では、脱炭焼鈍工程の前から仕上げ焼鈍の二次再結晶発現前までに（例えば、６００〜１０００℃の温度域の所定の温度の状態で）、窒化処理工程をさらに含んでもよい。具体的には、窒化処理工程は、脱炭焼鈍工程の前に独立して実施するか、脱炭焼鈍工程において加熱段階、均熱段階、冷却段階の１段階または複数の段階にて実施するか、脱焼鈍工程後に独立して実施するか、あるいは、焼鈍分離剤に窒素化合物を添加して仕上げ焼鈍工程の二次再結晶発現前までに実施してもよい。 Further, in the method for producing a directional electromagnetic steel plate according to the above-described embodiment, from before the decarburization annealing step to before the secondary recrystallization of finish annealing (for example, at a predetermined temperature in the temperature range of 600 to 1000 ° C.). In the state), the nitriding process may be further included. Specifically, whether the nitriding treatment step is carried out independently before the decarburization annealing step, or is carried out in one step or a plurality of steps of the heating step, the soaking step, and the cooling step in the decarburizing annealing step. , It may be carried out independently after the deannealing step, or it may be carried out before the secondary recrystallization of the finishing annealing step by adding a nitrogen compound to the annealing separator.

上述の実施形態の製造方法によって得られる方向性電磁鋼板は、主として変圧器その他の電気機器等の鉄心として利用できる。 The grain-oriented electrical steel sheet obtained by the manufacturing method of the above-described embodiment can be mainly used as an iron core of a transformer or other electric equipment.

以下、本発明の実施例を説明するが、実施例で採用した条件は、本発明の実施可能性及び効果を確認するための実施態様であり、本発明は、この実施態様に限定されるものではないことは自明である。 Hereinafter, examples of the present invention will be described, but the conditions adopted in the examples are embodiments for confirming the feasibility and effect of the present invention, and the present invention is limited to this embodiment. It is self-evident that it is not.

本発明者らは、珪素鋼板の表面における脱炭挙動に対し、脱炭焼鈍初期に形成される酸化層が以降の脱炭挙動に大きな影響を及ぼすものと考え、これに関連した種々の実験を行った。 The present inventors consider that the oxide layer formed at the initial stage of decarburization annealing has a great influence on the subsequent decarburization behavior with respect to the decarburization behavior on the surface of the silicon steel sheet, and various experiments related to this are performed. went.

＜実施例１＞
鋳造によって得られた質量で、Ｓｉ：３．３％、Ｍｎ：０．１４％、Ｃ：０．０５％、Ｓ：０．００７％、酸可溶性Ａｌ：０．０２７％、Ｎ：０．００８％を含有し、残部Ｆｅおよび不純物からなる珪素鋼スラブを加熱後、板厚２．０ｍｍまで熱間圧延した。この熱延板を１１００℃に加熱後９００℃に降温して３０秒保持する焼鈍を実施した後、最終板厚が０．２２ｍｍとなるように１回の冷間圧延を行った。<Example 1>
By mass obtained by casting, Si: 3.3%, Mn: 0.14%, C: 0.05%, S: 0.007%, acid-soluble Al: 0.027%, N: 0.008. A silicon steel slab containing% was heated and composed of the balance Fe and impurities, and then hot-rolled to a plate thickness of 2.0 mm. After heating this hot-rolled plate to 1100 ° C., lowering the temperature to 900 ° C. and holding it for 30 seconds, annealing was performed, and then cold rolling was performed once so that the final plate thickness was 0.22 mm.

この冷延板を、水素７５％及び窒素２５％を含有する雰囲気ガス中において、露点を変更することにより酸化度（ＰＨ２Ｏ／ＰＨ２）を変え、加熱速度７℃／秒で温度８３０℃まで昇温して１２０秒保持する脱炭焼鈍を行った。実施例１では、加熱帯の酸化度と均熱帯の酸化度とは等しい。 The degree of oxidation (PH2O / PH2 ) is changed by changing the dew point of this cold-rolled plate in an atmospheric gas containing 75% hydrogen and 25% nitrogen, and the temperature is up to 830 ° C at a heating rate of 7 ° C / sec. Dew point annealing was performed in which the temperature was raised and held for 120 seconds. In Example 1, the degree of oxidation in the heating zone is equal to the degree of oxidation in the tropics.

その後、アンモニアガス中にて鋼中窒素量を０．０２質量％まで高め（窒化処理）、インヒビターを強化した。 Then, the amount of nitrogen in the steel was increased to 0.02% by mass (nitriding treatment) in ammonia gas to strengthen the inhibitor.

この脱炭焼鈍板に、アルミナを主成分とする焼鈍分離剤（アルミナ８０質量％＋マグネシア２０質量％）を水スラリー状で塗布した後、水素７５％及び、窒素２５％を含有する雰囲気ガス中で１２００℃まで昇温し、水素１００％雰囲気ガス中に切り替えた後、１２００℃で２０時間焼鈍する仕上げ焼鈍を施した。 An annealing separator containing alumina as a main component (alumina 80% by mass + magnesia 20% by mass) is applied to this decarburized annealing plate in the form of an aqueous slurry, and then in an atmospheric gas containing 75% hydrogen and 25% nitrogen. The temperature was raised to 1200 ° C., and after switching to 100% hydrogen atmosphere gas, finish annealing was performed at 1200 ° C. for 20 hours.

以上の工程により作製された試料につき、水洗、試料剪断の後、さらに歪取り焼鈍を行い、さらに、鋼板に張力を与える絶縁被膜を形成した（張力コーティングを施した）後、レーザー照射を行い、ＳＳＴ法にて磁気測定を行った。脱炭焼鈍後の炭素量及び上記磁気測定によって得られた鉄損（Ｗ１７／５０）の値を表１に示す。The sample prepared by the above steps is washed with water, sheared, then strain-removed and annealed, and further, an insulating film that gives tension to the steel sheet is formed (tension-coated), and then laser irradiation is performed. Magnetic measurement was performed by the SST method. Table 1 shows the carbon content after decarburization annealing and the value of iron loss (W 17/50) obtained by the above magnetic measurement.

Figure 2020149320
Figure 2020149320

表１において、「Ｅｘ」は良好な結果であることを意味し、「Ｇ」は許容可能な範囲であることを意味し、「Ｂ」は好ましくない結果であることを意味する。 In Table 1, "Ex" means a good result, "G" means an acceptable range, and "B" means an unfavorable result.

表１より、酸化度が０．０１〜０．１５の湿潤ガス（水蒸気−水素−窒素混合ガス）雰囲気中で焼鈍した場合は、鋼板表面が平滑化しており、また炭素量も０．０２％以下に低減されているので仕上げ焼鈍中に変態して結晶方位が損なわれることも無く、０．７０Ｗ／ｋｇ以下の良好な鉄損が得られている。
しかしながら、鋼中炭素量が０．００３０％（３０ｐｐｍ）超となっているために、磁気時効（経時変化に伴う磁気特性の劣化）の懸念がある。
また、酸化度が０．２０以上の湿潤ガス雰囲気下で焼鈍した場合は、鋼中炭素量は０．００３０％以下となるが、良好な鉄損は得られていない。From Table 1, when annealed in a wet gas (water vapor-hydrogen-nitrogen mixed gas) atmosphere with an oxidation degree of 0.01 to 0.15, the surface of the steel plate is smooth and the carbon content is 0.02%. Since it is reduced to the following, the crystal orientation is not impaired by transformation during finish quenching, and a good iron loss of 0.70 W / kg or less is obtained.
However, since the amount of carbon in the steel exceeds 0.0030% (30 ppm), there is a concern about magnetic aging (deterioration of magnetic properties due to aging).
Further, when annealed in a moist gas atmosphere having a degree of oxidation of 0.20 or more, the carbon content in the steel is 0.0030% or less, but good iron loss is not obtained.

炭素量が０．００３０％以下に低減されない原因は、脱炭焼鈍の加熱過程で鋼板表面に形成される酸化物の質と形態とに依存するものと考えられる。脱炭焼鈍の表面においては、一般に脱炭（鋼中炭素の酸化）反応とシリカ等の酸化物形成（鋼中シリコンの酸化）反応が、雰囲気の水分に対して競合して行われている。
実施例１の結果より、鉄系酸化物が形成しないような低酸化度雰囲気ガス中で焼鈍すると、一般に鋼板表面のシリカは稠密な膜状で生成し、脱炭を阻害するものと考えられる。It is considered that the reason why the carbon content is not reduced to 0.0030% or less depends on the quality and morphology of the oxide formed on the surface of the steel sheet in the heating process of decarburization annealing. On the surface of decarburization annealing, a decarburization (oxidation of carbon in steel) reaction and an oxide formation of silica or the like (oxidation of silicon in steel) are generally carried out in competition with moisture in the atmosphere.
From the results of Example 1, it is considered that when annealed in a low-oxidation atmosphere gas that does not form an iron-based oxide, silica on the surface of the steel sheet is generally formed in the form of a dense film and inhibits decarburization.

＜実施例２＞
さらに、他の酸化物形成元素について検討を行い、Ｃｒを適量含有させることにより、鋼板表面にＣｒ酸化物を形成させ、シリカ形成反応を抑制することによって脱炭反応を促進させることを検討した。その結果を実施例２として以下に説明する。<Example 2>
Furthermore, other oxide-forming elements were investigated, and it was examined to form a Cr oxide on the surface of the steel sheet by containing an appropriate amount of Cr, and to promote the decarburization reaction by suppressing the silica formation reaction. The result will be described below as Example 2.

鋳造によって得られた質量で、Ｓｉ：３．３％、Ｍｎ：０．１４％、Ｃ：０．０５％、Ｓ：０．００７％、酸可溶性Ａｌ：０．０２７％、Ｎ：０．００８％、Ｃｒ：０．１２％を含有し、残部Ｆｅおよび不純物からなる珪素鋼スラブを加熱後、板厚２．０ｍｍまで熱間圧延した。この熱延板を１１００℃に加熱後９００℃に降温して３０秒保持する焼鈍を実施した後、最終板厚が０．２２ｍｍとなるように１回の冷間圧延を行った。 By mass obtained by casting, Si: 3.3%, Mn: 0.14%, C: 0.05%, S: 0.007%, acid-soluble Al: 0.027%, N: 0.008. A silicon steel slab containing%, Cr: 0.12% and composed of the balance Fe and impurities was heated and then hot-rolled to a plate thickness of 2.0 mm. After heating this hot-rolled plate to 1100 ° C., lowering the temperature to 900 ° C. and holding it for 30 seconds, annealing was performed, and then cold rolling was performed once so that the final plate thickness was 0.22 mm.

この冷延板を、水素７５％及び窒素２５％を含有する雰囲気ガス中において、露点を変更することにより酸化度（ＰＨ２Ｏ／ＰＨ２）を変え、加熱速度７℃／秒で温度８３０℃まで昇温して１２０秒保持する脱炭焼鈍を行った。実施例２では、加熱帯の酸化度と均熱帯の酸化度とは等しい。 The degree of oxidation (PH2O / PH2 ) is changed by changing the dew point of this cold-rolled plate in an atmospheric gas containing 75% hydrogen and 25% nitrogen, and the temperature is up to 830 ° C at a heating rate of 7 ° C / sec. Dew point annealing was performed in which the temperature was raised and held for 120 seconds. In Example 2, the degree of oxidation in the heating zone and the degree of oxidation in the tropics are equal.

その後、アンモニアガス中にて鋼中窒素量を０．０２質量％まで高め、インヒビターを強化した。 Then, the amount of nitrogen in the steel was increased to 0.02% by mass in ammonia gas to strengthen the inhibitor.

この脱炭焼鈍板に、アルミナを主成分とする焼鈍分離剤（アルミナ５０質量％＋マグネシア５０質量％）を水スラリー状で塗布した後、水素７５％及び窒素２５％を含有する雰囲気ガス中で１２００℃まで昇温し、その後、水素１００％雰囲気ガスに切り替えて１２００℃で２０時間焼鈍する仕上げ焼鈍を施した。以上の工程により作製された試料につき、水洗、試料剪断の後、さらに歪取り焼鈍を行い、さらに、鋼板に張力を与える絶縁被膜を形成した（張力コーティングを施した）後、レーザー照射を行い、ＳＳＴ法にて磁気測定を行った。脱炭焼鈍後の炭素量及び上記磁気測定によって得られた鉄損（Ｗ１７／５０）の値を表２に示す。An annealing separator containing alumina as a main component (alumina 50% by mass + magnesia 50% by mass) is applied to this decarburized annealing plate in the form of an aqueous slurry, and then in an atmospheric gas containing 75% hydrogen and 25% nitrogen. The temperature was raised to 1200 ° C., and then the gas was switched to 100% hydrogen atmosphere gas and subjected to finish annealing at 1200 ° C. for 20 hours. The sample prepared by the above steps is washed with water, sheared, then strain-removed and annealed, and further, an insulating film that gives tension to the steel sheet is formed (tension-coated), and then laser irradiation is performed. Magnetic measurement was performed by the SST method. Table 2 shows the carbon content after decarburization annealing and the value of iron loss (W 17/50) obtained by the above magnetic measurement.

Figure 2020149320
Figure 2020149320

表２において、「Ｅｘ」は良好な結果であることを意味し、「Ｇ」は許容可能な範囲であることを意味し、「Ｂ」は好ましくない結果であることを意味する。
表２より、珪素鋼素材にＣｒを適量含有させることによって、酸化度が０．０１〜０．１５の湿潤ガス（水蒸気−水素−窒素混合ガス）雰囲気中で焼鈍した場合は、良好な鉄損が得られると共に、鋼中炭素量が０．００３０％（３０ｐｐｍ）以下となることが分かる。In Table 2, "Ex" means a good result, "G" means an acceptable range, and "B" means an unfavorable result.
From Table 2, when an appropriate amount of Cr is contained in the silicon steel material and annealed in a wet gas (water vapor-hydrogen-nitrogen mixed gas) atmosphere having an oxidation degree of 0.01 to 0.15, good iron loss is obtained. It can be seen that the carbon content in the steel is 0.0030% (30 ppm) or less.

＜実施例３＞
実施例２において、含有させたＣｒは脱炭焼鈍の加熱過程で酸化物を形成して、脱炭反応を阻害するシリカ形成を抑制しているのではないかと推定された。そこで、加熱帯における雰囲気ガスの酸化度（Ｐ１＝ＰＨ２Ｏ／ＰＨ２）とＣｒ含有量との関係を検討した。<Example 3>
In Example 2, it was presumed that the contained Cr formed an oxide in the heating process of decarburization annealing and suppressed the formation of silica that inhibits the decarburization reaction. Therefore, the relationship between the degree of oxidation of the atmospheric gas (P1 = PH2O / PH2 ) in the heating zone and the Cr content was investigated.

鋳造によって得られた質量で、Ｓｉ：３．３％、Ｍｎ：０．１４％、Ｃ：０．０５％、Ｓ：０．００７％、酸可溶性Ａｌ：０．０２７％、Ｎ：０．００８％、Ｃｒ：０〜０．６２％を含有し、残部Ｆｅおよび不純物からなる珪素鋼スラブを加熱後、板厚２．０ｍｍまで熱間圧延した。この熱延板を１１００℃に加熱後９００℃に降温して３０秒保持する焼鈍を実施した後、最終板厚が０．２２ｍｍとなるように１回の冷間圧延を行った。 By mass obtained by casting, Si: 3.3%, Mn: 0.14%, C: 0.05%, S: 0.007%, acid-soluble Al: 0.027%, N: 0.008. %, Cr: 0 to 0.62%, and the silicon steel slab containing the balance Fe and impurities was heated and then hot-rolled to a plate thickness of 2.0 mm. After heating this hot-rolled plate to 1100 ° C., lowering the temperature to 900 ° C. and holding it for 30 seconds, annealing was performed, and then cold rolling was performed once so that the final plate thickness was 0.22 mm.

この冷延板を、水素７５％及び窒素２５％を含有する雰囲気ガス中において、加熱帯の露点を変更することにより酸化度（Ｐ１＝ＰＨ２Ｏ／ＰＨ２）を変え、加熱速度７℃／秒で温度８３０℃まで昇温した。雰囲気ガス酸化度（Ｐ２）を０．０６として、８３０℃で１２０秒に保持する脱炭焼鈍を行った。 The degree of oxidation (P1 = PH2O / PH2 ) was changed by changing the dew point of the heating zone in an atmospheric gas containing 75% hydrogen and 25% nitrogen, and the heating rate was 7 ° C./sec. The temperature was raised to 830 ° C. The atmospheric gas oxidation degree (P2) was set to 0.06, and decarburization annealing was carried out at 830 ° C. for 120 seconds.

その後、アンモニアガス中にて鋼中窒素量を０．０２質量％まで高め、インヒビターを強化した。 Then, the amount of nitrogen in the steel was increased to 0.02% by mass in ammonia gas to strengthen the inhibitor.

この脱炭焼鈍板に、アルミナを主成分とする焼鈍分離剤（アルミナ７０質量％＋マグネシア３０質量％）を水スラリー状で塗布した後、水素７５％及び、窒素２５％を含有する雰囲気ガス中で１２００℃まで昇温し、その後、水素１００％雰囲気ガスに切り替えて１２００℃で２０時間焼鈍する仕上げ焼鈍を施した。 An annealing separator containing alumina as a main component (70% by mass of alumina + 30% by mass of magnesia) is applied to this decarburized annealing plate in the form of an aqueous slurry, and then in an atmospheric gas containing 75% hydrogen and 25% nitrogen. After that, the temperature was raised to 1200 ° C., and then the gas was switched to 100% hydrogen atmosphere gas and annealed at 1200 ° C. for 20 hours for finish annealing.

以上の工程により作製された試料につき、水洗、試料剪断の後、さらに歪取り焼鈍を行い、さらに、絶縁被膜を形成した（張力コーティングを施した）後、レーザー照射を行い、ＳＳＴ法にて磁気測定を行った。 The sample prepared by the above steps is washed with water, sheared, then strain-removed and annealed, and further, after forming an insulating film (with tension coating), laser irradiation is performed, and the sample is magnetically subjected to the SST method. Measurements were made.

脱炭焼鈍後の炭素量が０．００３０％以下、及び鉄損（Ｗ１７／５０）が０．７０（Ｗ／ｋｇ）以下の良好な範囲を、図２のグラフに点線で囲まれた領域として示す。図２は、脱炭焼鈍後の炭素量と製品の鉄損とに及ぼす、Ｃｒ含有量Ｘ（質量％）と脱炭焼鈍の加熱帯の雰囲気ガス酸化度Ｐ１との関係性を示す図である。A good range of carbon content after decarburization annealing of 0.0030% or less and iron loss (W 17/50 ) of 0.70 (W / kg) or less is shown in the graph of FIG. 2 by a dotted line. Shown as. FIG. 2 is a diagram showing the relationship between the Cr content X (mass%) and the atmospheric gas oxidation degree P1 in the heating zone of decarburization annealing, which affects the carbon content after decarburization annealing and the iron loss of the product. ..

図２において、「〇」のプロットは、炭素量が０．００３０％以下、かつ鉄損（Ｗ１７／５０）が０．６５（Ｗ／ｋｇ）以下の良好な実験例、「□」のプロットは、炭素量が０．００３０％以下、かつ鉄損（Ｗ１７／５０）が０．６７（Ｗ／ｋｇ）以下の良好な実験例、「◇」のプロットは、炭素量が０．００３０％以下、かつ鉄損（Ｗ１７／５０）が０．７０以下の良好な実験例を示す。
図２において、「×」のプロットは、炭素量が０．００３０％超、あるいは鉄損（Ｗ１７／５０）が０．７０（Ｗ／ｋｇ）超の実験例を示す。In FIG. 2, the plot of “○” is a good experimental example in which the carbon content is 0.0030% or less and the iron loss (W 17/50 ) is 0.65 (W / kg) or less, and the plot of “□” is shown. Is a good experimental example in which the carbon content is 0.0030% or less and the iron loss (W 17/50 ) is 0.67 (W / kg) or less. The plot of "◇" shows the carbon content of 0.0030%. The following is a good experimental example in which the iron loss (W 17/50) is 0.70 or less.
In FIG. 2, the “x” plot shows an experimental example in which the carbon content exceeds 0.0030% or the iron loss (W 17/50 ) exceeds 0.70 (W / kg).

図２から、脱炭焼鈍の加熱帯の雰囲気ガスの酸化度Ｐ１（＝ＰＨ２Ｏ／ＰＨ２）とＣｒ含有量Ｘとの関係に応じた下記の式１の範囲で、脱炭焼鈍後の炭素量が０．００３０％以下、かつ鉄損（Ｗ１７／５０）が０．７０（Ｗ／ｋｇ）以下の良好な特性が得られることが分かる。
０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）From FIG. 2, the carbon after decarburization annealing is within the range of the following formula 1 according to the relationship between the oxidation degree P1 (= PH2O / PH2 ) of the atmospheric gas in the heating zone of decarburization annealing and the Cr content X. It can be seen that good characteristics with an amount of 0.0030% or less and an iron loss (W 17/50 ) of 0.70 (W / kg) or less can be obtained.
0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1)

また図２から、脱炭焼鈍の加熱帯の雰囲気ガスの酸化度Ｐ１（＝ＰＨ２Ｏ／ＰＨ２）とＣｒ含有量Ｘとの関係に応じた下記の式３の範囲で、脱炭焼鈍後の炭素量が０．００３０％以下、かつ鉄損（Ｗ１７／５０）が０．６７（Ｗ／ｋｇ）以下の良好な特性となることがわかる。図２では、この範囲を実線で囲まれた領域として示す。
０．３Ｘ＋０．０２５≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式３）Further, from FIG. 2, after decarburization annealing, it is within the range of the following formula 3 according to the relationship between the oxidation degree P1 (= PH2O / PH2 ) of the atmospheric gas in the heating zone of decarburization annealing and the Cr content X. It can be seen that the carbon content is 0.0030% or less and the iron loss (W 17/50 ) is 0.67 (W / kg) or less. In FIG. 2, this range is shown as a region surrounded by a solid line.
0.3X + 0.025 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 3)

＜実施例４＞
さらに、冷間圧延工程の特性への影響について検討した。その結果を以下に説明する。<Example 4>
Furthermore, the influence on the characteristics of the cold rolling process was examined. The results will be described below.

鋳造によって得られた質量で、Ｓｉ：３．３％、Ｍｎ：０．１％、Ｃ：０．０６％、Ｓ：０．００７％、酸可溶性Ａｌ：０．０２８％、Ｎ：０．００８％、Ｃｒ：０．１１％を含有し、残部Ｆｅおよび不純物からなる珪素鋼スラブを加熱後、板厚２．６ｍｍまで熱間圧延した。一部の熱延板については１１００℃で焼鈍（熱延板焼鈍）した後、板厚２．０ｍｍまで冷間圧延し、１１２０℃まで加熱後９５０℃に降温して３０秒保持する焼鈍（中間焼鈍）を行った後、更に最終板厚が０．２２ｍｍとなるように冷間圧延した（工程Ａ）。残りの熱延板については、熱延板焼鈍を施すことなく板厚２．０ｍｍまで冷間圧延し、１１２０℃まで加熱後９５０℃に降温して３０秒保持する焼鈍（中間焼鈍）を行った後、最終板厚が０．２２ｍｍとなるように冷間圧延した（工程Ｂ）。最終焼鈍後の冷間圧延率は、いずれの場合も８９％であった。 By mass obtained by casting, Si: 3.3%, Mn: 0.1%, C: 0.06%, S: 0.007%, acid-soluble Al: 0.028%, N: 0.008. A silicon steel slab containing%, Cr: 0.11% and composed of the balance Fe and impurities was heated and then hot-rolled to a plate thickness of 2.6 mm. Some hot-rolled plates are annealed at 1100 ° C (hot-rolled plate annealing), then cold-rolled to a plate thickness of 2.0 mm, heated to 1120 ° C, then lowered to 950 ° C and held for 30 seconds (intermediate). After annealing), cold rolling was performed so that the final plate thickness was 0.22 mm (step A). The remaining hot-rolled plate was cold-rolled to a plate thickness of 2.0 mm without annealing, heated to 1120 ° C, then lowered to 950 ° C and held for 30 seconds (intermediate annealing). After that, it was cold-rolled so that the final plate thickness was 0.22 mm (step B). The cold rolling ratio after final annealing was 89% in each case.

この冷延板を、水素７５％及び窒素２５％を含有する雰囲気ガス中において、０．０６の酸化度（ＰＨ２Ｏ／ＰＨ２）で、加熱速度３０℃／秒で温度８３０℃まで昇温して１２０秒保持する脱炭焼鈍を行った。実施例４では、加熱帯の酸化度と均熱帯の酸化度とは等しい。This cold-rolled plate is heated to a temperature of 830 ° C. at a heating rate of 30 ° C./sec at an oxidation degree of 0.06 (PH2O / PH2 ) in an atmospheric gas containing 75% hydrogen and 25% nitrogen. Decarburization annealing was performed, which was held for 120 seconds. In Example 4, the degree of oxidation in the heating zone is equal to the degree of oxidation in the tropics.

その後、アンモニアガス中にて鋼中窒素量を０．０２５質量％まで高め、インヒビターを強化した。 Then, the amount of nitrogen in the steel was increased to 0.025% by mass in ammonia gas to strengthen the inhibitor.

この脱炭焼鈍板に、アルミナを主成分とする焼鈍分離剤（アルミナ９０質量％＋マグネシア１０質量％）を水スラリー状で塗布した後、水素７５％及び窒素２５％を含有する雰囲気ガス中で１２００℃まで昇温し、その後、水素１００％雰囲気ガスに切り替えて１２００℃で２０時間焼鈍する仕上げ焼鈍を施した。
以上の工程により作製された試料につき、水洗、試料剪断の後、さらに歪取り焼鈍を行い、さらに、鋼板に張力を与える絶縁被膜を形成した（張力コーティングを施した）後、レーザー照射を行い、ＳＳＴ法にて磁気測定を行った。
脱炭焼鈍後の炭素量及び上記磁気測定によって得られた鉄損（Ｗ１７／５０）の値を表３に示す。An annealing separator containing alumina as a main component (90% by mass of alumina + 10% by mass of magnesia) is applied to this decarburized annealing plate in the form of an aqueous slurry, and then in an atmospheric gas containing 75% hydrogen and 25% nitrogen. The temperature was raised to 1200 ° C., and then the gas was switched to 100% hydrogen atmosphere gas and subjected to finish annealing at 1200 ° C. for 20 hours.
The sample prepared by the above steps is washed with water, sheared, then strain-removed and annealed, and further, an insulating film that gives tension to the steel sheet is formed (tension-coated), and then laser irradiation is performed. Magnetic measurement was performed by the SST method.
Table 3 shows the carbon content after decarburization annealing and the value of iron loss (W 17/50) obtained by the above magnetic measurement.

Figure 2020149320
Figure 2020149320

表３において、「Ｅｘ」は良好な結果であることを意味する。
表３に示す通り、いずれの工程を経た場合でも、脱炭後の鋼中炭素量が０．００３０％（３０ｐｐｍ）以下となるとともに、良好な鉄損が得られた。In Table 3, "Ex" means good results.
As shown in Table 3, the carbon content in the steel after decarburization was 0.0030% (30 ppm) or less and good iron loss was obtained regardless of which step was passed.

＜実施例５＞
さらに、珪素鋼スラブの成分の特性への影響について検討した。その結果を実施例５として以下に説明する。<Example 5>
Furthermore, the influence on the characteristics of the components of the silicon steel slab was investigated. The result will be described below as Example 5.

鋳造によって得られた、表４に示す成分を含有し、残部Ｆｅおよび不純物からなる珪素鋼スラブを加熱後、板厚２．３ｍｍまで熱間圧延した。この熱延板を１１２０℃まで加熱後９５０℃まで降温して３０秒保持する焼鈍を実施した後、最終板厚が０．２２ｍｍとなるように１回の冷間圧延を行った。 A silicon steel slab containing the components shown in Table 4 obtained by casting and composed of the balance Fe and impurities was heated and then hot-rolled to a plate thickness of 2.3 mm. After heating this hot-rolled plate to 1120 ° C., lowering the temperature to 950 ° C. and holding it for 30 seconds, annealing was performed, and then cold rolling was performed once so that the final plate thickness was 0.22 mm.

この冷延板を、水素７５％及び窒素２５％を含有する雰囲気ガス中において、０．１０の酸化度（ＰＨ２Ｏ／ＰＨ２）で、加熱速度３０℃／秒で温度８３０℃まで昇温した後、０．０６の酸化度（ＰＨ２Ｏ／ＰＨ２）に切り替えて１２０秒保持する脱炭焼鈍を行った。This cold-rolled plate was heated to a temperature of 830 ° C. at a heating rate of 30 ° C./sec at an oxidation degree of 0.10 (PH2O / PH2 ) in an atmospheric gas containing 75% hydrogen and 25% nitrogen. After that, decarburization annealing was performed by switching to an oxidation degree of 0.06 ( PH2O / PH2) and holding for 120 seconds.

その後、アンモニアガス中にて鋼中窒素量を０．０２５質量％まで高め、インヒビターを強化した。 Then, the amount of nitrogen in the steel was increased to 0.025% by mass in ammonia gas to strengthen the inhibitor.

この脱炭焼鈍板に、アルミナを主成分とする焼鈍分離剤（アルミナ６０質量％＋マグネシア４０質量％）を水スラリー状で塗布した後、水素７５％及び窒素２５％を含有する雰囲気ガス中で１２００℃まで昇温し、その後、水素１００％雰囲気ガスに切り替えて１２００℃で２０時間焼鈍する仕上げ焼鈍を施した。
以上の工程により作製された試料につき、水洗、試料剪断の後、さらに歪取り焼鈍を行い、さらに、鋼板に張力を与える絶縁被膜を形成した（張力コーティングを施した）後、レーザー照射を行い、ＳＳＴ法にて磁気測定を行った。
脱炭焼鈍後の炭素量及び上記磁気測定によって得られた鉄損（Ｗ１７／５０）の値を表４に示す。An annealing separator containing alumina as a main component (60% by mass of alumina + 40% by mass of magnesia) is applied to this decarburized annealed plate in the form of an aqueous slurry, and then in an atmospheric gas containing 75% hydrogen and 25% nitrogen. The temperature was raised to 1200 ° C., and then the gas was switched to 100% hydrogen atmosphere gas and subjected to finish annealing at 1200 ° C. for 20 hours.
The sample prepared by the above steps is washed with water, sheared, then strain-removed and annealed, and further, an insulating film that gives tension to the steel sheet is formed (tension-coated), and then laser irradiation is performed. Magnetic measurement was performed by the SST method.
Table 4 shows the carbon content after decarburization annealing and the value of iron loss (W 17/50) obtained by the above magnetic measurement.

Figure 2020149320
Figure 2020149320

表４に示すように、いずれの組成の珪素鋼スラブを用いた場合でも、脱炭後の鋼中炭素量が０．００３０％（３０ｐｐｍ）以下となるとともに、良好な鉄損が得られた。 As shown in Table 4, regardless of the composition of the silicon steel slab, the carbon content in the steel after decarburization was 0.0030% (30 ppm) or less, and good iron loss was obtained.

以上の結果より、冷間圧延後の材料の鋼中に含まれる炭素を除去するために、湿水素雰囲気中で脱炭焼鈍を行う脱炭焼鈍工程において、Ｃｒを適量含有させるとともに、脱炭焼鈍工程の加熱帯の雰囲気ガスの酸化度Ｐ１、さらに、均熱帯の雰囲気ガスの酸化度Ｐ２を鉄系酸化物が形成されない酸化度に制御することによって、脱炭反応を安定的に行わせるとともに鋼板表面の平滑化を促進して良好な鉄損特性の製品を製造することが可能となることがわかった。 From the above results, in the decarburization annealing step of decarburization annealing in a wet hydrogen atmosphere in order to remove carbon contained in the steel of the material after cold rolling, an appropriate amount of Cr is contained and decarburization annealing is performed. By controlling the degree of oxidation P1 of the atmosphere gas in the heating zone of the process and the degree of oxidation P2 of the atmosphere gas in the temperate tropical zone to the degree of oxidation in which iron-based oxides are not formed, the decarburization reaction is stably performed and the steel sheet is formed. It was found that it is possible to promote surface smoothing and produce a product with good iron loss characteristics.

Claims (6)

珪素鋼素材を製造する珪素鋼素材製造工程と、
前記珪素鋼素材を熱間圧延して熱延板を得る熱間圧延工程と、
前記熱延板に一回の冷間圧延もしくは中間焼鈍を挟む複数回の冷間圧延を施して最終板厚の鋼板を得る冷間圧延工程と、
前記鋼板に、加熱帯と均熱帯を備える脱炭焼鈍炉を用いて脱炭焼鈍を施す脱炭焼鈍工程と、
前記鋼板に、アルミナを主成分とする焼鈍分離剤を塗布し、仕上げ焼鈍を施す仕上げ焼鈍工程と、を含み、
前記珪素鋼素材が、質量％で、
Ｓｉ：０．８〜７．０％、
Ｃ：０．０８５％以下、
酸可溶性Ａｌ：０．０１０〜０．０６５％、
Ｎ：０．００４〜０．０１２％、
Ｍｎ：１．００％以下、
Ｓ：０．０５０％以下、および
Ｃｒ：０．０２〜０．５０％、
を含有し、残部がＦｅ及び不純物からなり、
前記脱炭焼鈍工程では、
前記珪素鋼素材のＣｒ含有量を質量％でＸとしたとき、前記加熱帯の雰囲気ガスの酸化度Ｐ１が下記の式１を満足し、かつ前記均熱帯の雰囲気ガスの酸化度Ｐ２が下記の式２を満足する
ことを特徴とする方向性電磁鋼板の製造方法。
０．１８Ｘ−０．００８≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式１）
０．０１≦Ｐ２≦０．１５ （式２）The silicon steel material manufacturing process that manufactures silicon steel materials, and
The hot rolling process of hot rolling the silicon steel material to obtain a hot rolled plate,
A cold rolling step of obtaining a steel plate having a final plate thickness by subjecting the hot-rolled sheet to one cold rolling or multiple times of cold rolling with intermediate annealing sandwiched between them.
A decarburization annealing step of performing decarburization annealing on the steel sheet using a decarburization annealing furnace equipped with a heating zone and a tropic.
The steel sheet includes a finish annealing step of applying an annealing separator containing alumina as a main component and performing finish annealing.
The silicon steel material is by mass%
Si: 0.8-7.0%,
C: 0.085% or less,
Acid-soluble Al: 0.010 to 0.065%,
N: 0.004 to 0.012%,
Mn: 1.00% or less,
S: 0.050% or less, and Cr: 0.02 to 0.50%,
The balance consists of Fe and impurities.
In the decarburization annealing step,
When the Cr content of the silicon steel material is X by mass%, the oxidation degree P1 of the atmospheric gas in the heating zone satisfies the following formula 1, and the oxidation degree P2 of the atmospheric gas in the tropical zone is as follows. A method for manufacturing a grain-oriented electrical steel sheet, which is characterized by satisfying the formula 2.
0.18X-0.008 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 1)
0.01 ≤ P2 ≤ 0.15 (Equation 2) 前記Ｐ１が下記の式３を満足することを特徴とする請求項１に記載の方向性電磁鋼板の製造方法。
０．３Ｘ＋０．０２５≦Ｐ１≦０．２５Ｘ＋０．１５≦０．２０ （式３）The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, wherein P1 satisfies the following formula 3.
0.3X + 0.025 ≤ P1 ≤ 0.25X + 0.15 ≤ 0.20 (Equation 3) 前記Ｐ１、および前記Ｐ２が下記の式４を満足する
ことを特徴とする請求項１又は２に記載の方向性電磁鋼板の製造方法。
Ｐ１＞Ｐ２ （式４）The method for manufacturing a grain-oriented electrical steel sheet according to claim 1 or 2, wherein the P1 and the P2 satisfy the following formula 4.
P1> P2 (Equation 4) 前記珪素鋼素材が、さらに、質量％で、
Ｃｕ：０％以上０．４％以下、
Ｐ：０％以上０．５％以下、
Ｎｉ：０％以上１．０％以下、
Ｂ：０％以上０．００８％以下、
Ｖ：０％以上０．１５％以下、
Ｎｂ：０％以上０．２０％以下、
Ｍｏ：０％以上０．１０％以下、
Ｔｉ：０％以上０．０１５％以下、及び
Ｂｉ：０％以上０．０１０％以下、
を含有する
ことを特徴とする請求項１から３のいずれか１項に記載の方向性電磁鋼板の製造方法。The silicon steel material is further increased by mass%.
Cu: 0% or more and 0.4% or less,
P: 0% or more and 0.5% or less,
Ni: 0% or more and 1.0% or less,
B: 0% or more and 0.008% or less,
V: 0% or more and 0.15% or less,
Nb: 0% or more and 0.20% or less,
Mo: 0% or more and 0.10% or less,
Ti: 0% or more and 0.015% or less, and Bi: 0% or more and 0.010% or less,
The method for manufacturing a grain-oriented electrical steel sheet according to any one of claims 1 to 3, which comprises. 前記脱炭焼鈍工程の前から前記仕上げ焼鈍工程での二次再結晶発現前までに、窒化処理工程をさらに含む
ことを特徴とする請求項１から４のいずれか１項に記載の方向性電磁鋼板の製造方法。The directional electromagnetic steel according to any one of claims 1 to 4, further comprising a nitriding treatment step from before the decarburization annealing step to before the secondary recrystallization manifestation in the finish annealing step. Steel sheet manufacturing method. 前記熱間圧延工程の後、かつ前記冷間圧延工程の前に、前記熱間圧延工程で得られた前記熱延板を焼鈍する熱延板焼鈍工程をさらに含む
ことを特徴とする請求項１から５のいずれか１項に記載の方向性電磁鋼板の製造方法。Claim 1 is further comprising a hot-rolled plate annealing step of annealing the hot-rolled plate obtained in the hot-rolled step after the hot-rolling step and before the cold-rolling step. The method for manufacturing a directional electromagnetic steel sheet according to any one of 5 to 5.
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